linux-kernel - Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection at probe

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Date:   Wed, 18 Sep 2019 10:17:01 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Yauhen Kharuzhy <jekhor@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection
 at probe

On Wed, Sep 18, 2019 at 2:04 AM Yauhen Kharuzhy <jekhor@...il.com> wrote:
>
> On Tue, Sep 17, 2019 at 02:13:22PM +0300, Andy Shevchenko wrote:
> > On Tue, Sep 17, 2019 at 12:15:36AM +0300, Yauhen Kharuzhy wrote:
> > > Intel Cherry Trail Whiskey Cove extcon driver connect USB data lines to
> > > PMIC at driver probing for further charger detection. This causes reset of
> > > USB data sessions and removing all devices from bus. If system was
> > > booted from Live CD or USB dongle, this makes system unusable.
> > >
> > > Check if USB ID pin is floating and re-route data lines in this case
> > > only, don't touch otherwise.
> >
> > > +   ret = regmap_read(ext->regmap, CHT_WC_PWRSRC_STS, &pwrsrc_sts);
> > > +   if (ret) {
> > > +           dev_err(ext->dev, "Error reading pwrsrc status: %d\n", ret);
> > > +           goto disable_sw_control;
> > > +   }
> > > +
> > > +   id = cht_wc_extcon_get_id(ext, pwrsrc_sts);
> >
> > We have second implementation of this. Would it make sense to split to some
> > helper?
>
> Do you mean the combination of regmap_read(...CHT_WC_PWRSRC_STS,
> &pwrsrc_sts) with cht_wc_extcon_get_id()?

Yes.

> In the cht_wc_extcon_pwrsrc_event() function the pwrsrc_sts is checked
> for other bits also, so separation of PWRSRC_STS read and id calculation
> to one routine will cause non-clear function calls like as
> get_powersrc_and_check_id(..., &powersrc_sts, &id) which is not looks
> better than current code duplication.

I see. Thanks for answer.

> Or we need to spend some time for
> refactoring and testing of cht_wc_extcon_pwrsrc_event() code.

Perhaps, In any case I'm not objecting of the current approach.

-- 
With Best Regards,
Andy Shevchenko